The long term objective of this project is to explore the biochemistry and function of lipids in saliva and salivary concretions in health and disease, and to define the relationship of these lipids to the protein and glycoprotein components. The specific goals set for the proposed period are: to establish the role of covalently bound and associated lipids in the buoyant density, viscosity and hydrophobic behavior of salivary mucins from caries-resistant (CR) and caries-susceptible (CS) subjects; to evaluate the effect of covalently bound and associated lipids on the susceptibility of salivary mucins to proteolytic degradation; to isolate and characterize lipoproteins of parotid saliva from CR and CS subjects; to determine the composition and content of lipids covalently bound and associated with proline-rich glycoprotein of parotid saliva, and assess differences with caries; to investigate the relationship of lipids to proteins and glycoproteins in tooth enamel pellicle; to evaluate the role of pellicle mucin and lipoprotein components in the retardation of cariogenic acids diffusion and the contribution of lipids to this function of pellicle; to characterize lipids of the mucous layer covering human oral epithelium, explore their origin and relationship to other constituents, and determine rheological and permselective properties of this mucous layer; to investigate changes in lipids of the oral mucous layer in subjects with aphthous stomatitis; to study substrate specificity, subcellular location and kinetics of the enzyme responsible for the acylation of salivary glycoproteins with fatty acids in rat salivary glands; to conduct the measurements of the acyltransferase activity in salivary gland biopsies of patients with salivary gland and systemic disease; to measure the activities of enzymes responsible for sulfation of secretory and structural glycolipids in salivary glands of patients with salivary gland and systemic disease; and to pursue studies on lipids and their relation to proteins and glycoproteins in the secretions of the major and minor salivary glands of patients with salivary gland and systemic diseases.